Abstract A70: Smoking, body mass index, and breast cancer risk: A pooled analysis of Hispanic and non-Hispanic white women from New Mexico.

Abstract

Abstract Obesity has been identified as a well-known modifiable risk factor for postmenopausal breast cancer. The association between smoking and breast cancer also has been extensively studied in epidemiological literature. The compounded relationship between smoking and obesity with breast cancer risk has been of interest in recent studies; however ethnic/racial differences with this potential interaction have not been investigated. We evaluated the interaction between active smoking and obesity measured by body mass index (BMI) and risk of breast cancer in Hispanic (H) and non-Hispanic white (NHW) women from New Mexico. Data on smoking exposure, BMI (kg/m2), and other lifestyle/behavioral risk factors were available from a pooled sample of 1,699 incident breast cancer cases (1011 NHW, 688 H) and 1,772 population based-controls (1066 NHW, 706 H) from the New Mexico Women's Health Study (1992-1994) and the 4-Corner's Breast Cancer Study (1999-2004). Using multivariable logistic regression, odds ratios (ORs) and 95% Confidence Intervals (CI) were calculated to estimate the risk of breast cancer by active smoking exposures between normal weight (BMI< 25), overweight (BMI=25-29.9), and obese (BMI≥30) women. We also tested for interaction effects between smoking, BMI, and ethnicity. All models were adjusted for age, study, menopausal status, alcohol intake, education, physical activity, calories consumed/day, and parity. There were significant (p value < 0.001) differences between H and NHW women for BMI categories, smoking status, total pack years, total number of smoking years, and average number of cigarettes/day. Overall, we did not find significant interaction effects between BMI and smoking or between BMI, smoking, and ethnicity. However, overweight H women who were former smokers compared to never smokers did have an inverse association with breast cancer risk (OR, 0.62; 95% CI 0.39-0.99). We also observed inverse associations for breast cancer among overweight H women who smoked less than 10 years (OR, 0.42; 95% CI 0.21-0.84), less than 10 pack years (OR, 0.56; 95% CI 0.34-0.92), and less than 15 cigarettes/day (OR, 0.63; 95% CI 0.41-0.98). Obese H women who smoked between 30-49 years also had a reduced risk for breast cancer (OR, 0.44; 95% CI 0.22-0.89). No significant associations were found among NHW women within our stratified analysis. Our data suggest that the interaction effects between ethnicity, BMI, and smoking are not statistically significant; however, overweight H women who previously smoked or who had limited active smoking exposure may have some decrease in risk of breast cancer. Citation Format: Avonne E. Connor, Christina M. Pinkston, Richard N. Baumgartner, Kathy B. Baumgartner. Smoking, body mass index, and breast cancer risk: A pooled analysis of Hispanic and non-Hispanic white women from New Mexico. [abstract]. In: Proceedings of the Fifth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2012 Oct 27-30; San Diego, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(10 Suppl):Abstract nr A70.